This invention relates to prosthetic devices for medializing a vocal cord, and more particularly to a preformed and presized prosthetic device for obtaining optimum displacement of a vocal cord to correct dysphonia due to vocal cord dysfunction.
Vocal cords or vocal folds normally undergo dynamic movement between a relatively closed phonation position and a relatively open breathing position to allow an individual to speak and breathe. Phonation generally occurs when the vocal cords are in their relatively closed position, which obstructs the flow of air. Thus normal breathing is difficult when phonation occurs. Breathing is facilitated when phonation is interrupted to enable the vocal cords to move to their relatively open position. Vocal cord dysfunction or dysphonia usually occurs when one of the vocal cords is paralyzed and recedes into a slightly divergent open position resulting in reduced phonation capability.
In one known treatment of vocal cord dysfunction, a laryngoplasty is performed wherein an implant such as a silicone block is installed between the thyroid cartilage and the paralyzed vocal cord to medialize the vocal cord. The shaping and sizing of the implant is usually a manual procedure performed by the surgeon on an empirical basis who custom forms the prosthesis based on an estimate of the amount of medialization needed by the patient.
A preliminary version of the implant is inserted between the vocal cord and the thyroid cartilage and the patient's phonation ability is evaluated. If there is a need for further medialization the prosthesis is removed and resized and/or reshaped and again inserted between the vocal cord and the thyroid cartilage for further evaluation of the patient's phonation ability.
Often two or more insertions and modifications of an implant are made in this manner in order to obtain the desired medialization.
A problem that arises in connection with each insertion and subsequent removal of an implant is that the patient can suffer trauma and tissue edema. Swelling of tissue often leads to a false determination of optimum size for an implant. For example, when tissue edema recedes it may become apparent that there is an undercorrection of the vocal cord medialization because the tissue edema caused a false reading of implant requirements. Thus one of the greatest difficulties with current laryngoplasty techniques is that an implant must be repeatedly inserted in a patient and modified in accordance with empirical assessments of required medialization.
It is thus desirable to provide a preformed and presized prosthesis for medializing a vocal cord and a tool for displacing a vocal cord to an optimal phonation position and measuring the amount of displacement to permit use of the presized prosthesis.